Projection optical printing apparatus

ABSTRACT

Projection optical printing apparatus which may be employed for variable enlargement and reduction of a projected image to which light sensitive material is exposed. The optical system of this apparatus comprises, in succession along the optical axis a light beam path, the following optical elements including an apertured support for a film print, e.g., a projector head film gate. This film print bears an image to be recorded with this support extending in a print plane transversely of and substantially normal to the optical axis with the latter extending substantially through the center of the support aperture. This film print support is followed by a printing lens substantially axially aligned with the optical axis, and, thereafter, a transversely extending support for light sensitive material, e.g., a camera film gate, through the center of which the optical axis extends and located at a plane of printing reproductions by the printing lens. Suitable mechanism is provided to translate along the optical axis one or more of these units, i.e., the light sensitive material support, the printing lens and the film print support relative to the others thereof. An improved light source sub-assembly is embodied in such apparatus at a position preceding the film print support or projector film gate. This light source sub-assembly includes a source of light rays to which the light sensitive material responds for recording thereon a replica of the projected image, and means providing in a transverse plane an in-focus image of the light source preceding the film print plane, such as that at the location of the source of light rays or thereafter as may be effected by focusing lens means in a focal plane at the second principal focus of the latter. This light source sub-assembly also includes a mechanically adjustable light valve in the light source image plane which embodies light-blocking and masking transverse means having opposed edges located at substantially equal distances on opposite sides of the optical axis to define an intervening light-passing space. The portions of this light valve means which have the opposed edges are simultaneously movable both directionally toward and away from the optical axis and in extent at equal increments of continuous motion for infinite variability of the intervening light-passing space. For automatic adjustment of the opening of the light source valve a servomotor system may be provided advantageously which includes light valve control means automatically to adjust the opening in the latter in response to adjustment of the camera gate along the optical axis. A sophisticated version of this servomotor system for the printer which includes the pair of projector heads may embody a first output signal generator, such as a potentiometer, which is manipulated by adjustment of the camera gate along the optical axis, light valve opening adjustment mechanism, a second output signal generator, such as another potentiometer, manipulated by the light valve adjustment mechanism, and electrical circuit means connected to the output signal generators for combining the output signals thereof to produce a circuit output signal, with the means which automatically adjusts the opening of the light valve responding to the circuit output signal. A third Output signal generator, such as still another potentiometer, is manipulated by the independently adjustable transfer lens between the projector heads and the output signal therefrom is combined in the circuit means with the other output signals to provide the circuit output signal which dictates the adjustment of the light valve opening.

United States Patent Oxberry et al.

154] PROJECTION OPTICAL PRINTING APPARATUS [72] inventors: John W.Oxberry, New Rochelle, N.Y.; Werner K. Bender, Carlisle, Mass; StanislawA. Policht, Closter,

[73] Assignee: Berkey Photo Inc., New York, N.Y. [22] Filed: March 10,1969 211 Appl. No; 805,689

Primary ExaminerSamuel S. Matthews Assistant Examiner-Richard A.Wintercom Attorney-Watson, Leavenworth and Kelton [5 7] ABSTRACTProjection optical printing apparatus which may be employed for variableenlargement and reduction of a projected image to which light sensitivematerial is exposed. The optical system of this apparatus comprises, insuccession along the optical axis a light beam path, the followingoptical elements including an apertured support for a film print, e.g.,a projector head film gate. This film print bears an image to berecorded with this support extending in a print plane transverse ly ofand substantially normal to the optical axis with the latter extendingsubstantially through the center of the support aperture. This filmprint support is followed by a printing lens substantially axiallyaligned with the optical axis, and, thereafter, a transversely extendingsupport for light sensitive material, e.g., a camera film gate, throughthe center of which the optical axis extends and located at a plane ofprinting [45. Aug. 8, 1972 reproductions by the printing lens. Suitablemechanism is provided to translate along the optical axis one or more ofthese units, i.e., the light sensitive material support, the printinglens and the film print support relative to the others thereof. Animproved light source sub-assembly is embodied in such apparatus at aposition preceding the film print support or projector film gate. Thislight source sub-assembly includes a source of light rays to which thelight sensitive material responds for recording thereon a replica of theprojected image, and means providing in a transverse plane an in-focusimage of the light source preceding the film print plane, such as thatat the location of the source of light rays or thereafter as may beeffected by focusing lens means in a focal plane at the second principalfocus of the latter. This light source sub-assembly also includes amechanically adjustable light valve in the light source image planewhich embodies light-blocking and masking transverse means havingopposed edges located at substantially equal distances on opposite sidesof the optical axis to define an intervening light-passing space. Theportions of this light valve means which have the opposed edges aresimultaneously movable both directionally toward and away from theoptical axis and in extent at equal increments of continuous motion forinfinite variability of the intervening light-passing space.

For automatic adjustment of the opening of the light source valve aservomotor system may be provided advantageously which includes lightvalve control means automatically to adjust the opening in the latter inresponse to adjustment of the camera gate along the optical axis. Asophisticated version of this servomotor system for the printer whichincludes the pair of projector heads may embody a first output signalgenerator, such as a potentiometer, which is manipulated by adjustmentof the camera gate along the optical axis, light valve openingadjustment mechanism, a second output signal generator, such as anotherpotentiometer, manipulated by the light valve adjustment mechanism, andelectrical circuit means connected to the output signal generators forcombining the output signals thereof to produce a circuit output signal,with the means which automatically adjusts the opening of the lightvalve responding to the circuit output signal. A third output signalgenerator, such as still another potentiometer, is manipulated by theindependently adjustable transfer lens between the projector heads andthe output signal therefrom is combined in the circuit means with theother output signals to provide the circuit output signal which dictatesthe adjustment of the light valve opening.

18 Claim, 11 Drawing Figures 151 3,682,540 45 Aug. 8, 1972 United StatesPatent Oxberry et al.

CAMERA II PROJECTOR I0 PATENTEDms 8 I972 3.682.540

" sum 5 or 6 FIG. 6

1 PROJECTION OPTICAL PRINTING APPARATUS In optical printing techniquesattained with the operation of projectional optical printing apparatus,such as a projection optical printer, obtainment and maintenance of aproper value of light intensity and even distribution thereof at atransversely extending support for light sensitive material in which aprojected image is to be recorded, such as a camera gate having anopening in which a frame of a raw stock film is exposed, are desiredoptimums.

It is a common practice to provide prior optical systems of projectionoptical printers with a set of condensers just ahead of the lamphouse tocollect the light rays delivered from the latter and pass them on alongan optical axis in a compact bundle or beam successively to one or moreprojector gates, across the opening of each of which an image-bearingstrip film is translated, a camera or printing lens, and a camera gate,to a raw stock film which is translated across the opening of thelatter. Deliberate changes in the density of the light at the raw stockprinting plane are demanded in the practice of projection printingtechniques. If a film being translated through the projector head isdarker in certain sections than skilled judgment dictates, a greaterdensity of the printing light is demanded for printing these sectionsthan is required for the lighter sections, and the attainment of desiredcontrasts make similar requirements. In operating prior projectionoptical printers light density adjustments have been of two types, i.e.,(l) to adjust the opening of an iris diaphragm in the printing lensassembly, (2) to vary the voltage imposed upon the electrical lightsource bulb, (3) to employ a neutral density filter, (4) variable camerashutter, and (5) adjustment of the exposure time.

Adjusting the opening of an iris diaphragm in the printing lens assemblyposes many undesirable problems. Such adjustments are recognized as fstop changes. There are 12 points or units in a single f stop, and onepoint is expressed by the formula 0.025 Log. E where E indicates theillumination in recognized arbitrary units. In passing light raysthrough the iris opening those which strike the edges of the iris bladesand pass through are deviated slightly. Consequently, the focal lengthof the printing lens is changed thereby, which causes a change in thesize of the image at the camera gate. If the camera is zoomed in forprogressive blowup or zoomed out for retrogressive reduction this imagesize change is progressive. Zoom changes in focus due to f stop changesresulting from iris adjustments for light compensation require laboriousand time consuming operator manipulations, and demand extreme skill. Forsuch reason, and others, the zooming of the camera of such simplifiedoptical printing system characterized by a single projector head isquite consistently avoided, especially when matte work is practiced.

In the use of a printing optical system which involves the use of aplurality of projector heads, including one or more aerial imageprojector heads for translation of one or more mattes therethrough, suchas that proposed in the Oxberry US. Pat. No. 3,040,619 of June 26, 1962,the problems developed by adjustment of the iris diaphragm in theprinting lens assembly become more complicated. This is equally truewith respect to a plural projector head optical system wherein theprojecting section of this Oxberry patent printing system additionallyis embodied in a secondary duplicate of the primary projecting section,whereby these primary and secondary projecting sections additivelyimpose their combined outputs on the raw stock film being printed in thesingle camera. This secondary projecting section, as in primaryprojecting section employed in the Oxberry patent system, includes, insuccession, its own source of light rays, an aerial image projectorhead, an axially adjustable transfer lens and a relatively fixed masterprojector head having an associated field lens, and it may be embodiedwith the primary projecting section by inserting an oblique lighttransmitting and reflective mirror, e.g., a beam splitter, between thegate of the master projector head of the primary projecting section andthe printing lens. The output of this secondary projecting section isdirected toward the oblique reflecting interface of the beam splitterfor combining thereat its transmitted image with that transmitted by theOxberry patent primary projecting section for projection of the combinedimages to the camera raw stock film. The black core matte film, havingan opaqued area of a desired or wanted foreground image surrounded by animage-free transparent field, may be translated through the aerial imageprojector head of the primary projecting section, and the film bearingthe complete background image may be translated through the masterprojector head of this section. The white core matte film, having animage-free transparent area of the wanted foreground image surrounded byan opaque ground or field, may be translated through the aerial imageprojector head of the additive secondary projecting section, and thefilm bearing the wanted foreground image surrounded by an unwanted imageof the studio setting (the latter of which is to be eliminated by thesurrounding opaque field of the white core matte) may be translatedthrough the master projector head of this secondary projecting section.The outlines of the wanted foreground image and of the white core andblack core areas of the mattes which correspond to this foreground imagemust be matched to within about twenty millionths of an inch (0.00002inch) of each other, i.e., of the order of light wavelengths, and thisexactitude of matching must be maintained during in and out zoom shots,in order to avoid undesirable features in printed films of the assembledbackground and foreground images. A skilled operator attains suchmatching by the observation of showings of color to guide adjustments.

Operation of prior printing systems of such projection optical printersdo not maintain such a degree of matching during zooms because of theneed in the progress of the latter of repeated changing of the f stop ofthe iris diaphragm in the printing lens is a ready manner of identifyingthe total angular photographic field produced thereby it is apparentthat the lens focal length changes resulting from f stop alterationseffect changes of the total angular photographic field. This resultsfrom the attendant change in the angle of incidence of the marginallight rays of the beam passed through the changing size of the openingin the iris diaphragm. In the practice of full color printing with suchprior printing systems employing a 1:1 ratio printing lens if theoutlines of the black matte core are precisely matched with the marginsof the foreground image insert at a certain f stop, in progressingthrough a reduction of image size, the f stop opening is progressivelyreduced to cause development of an undesirable black halo about themargins of the foreground image insert in the printed camera film as aresult of the black core area image being too large. Also, out of focuscondition is progressively developed and even intensity of thephotographic field deteriorates, such as to produce mottled density ofthis field. In full color printing, if the black core area image becomestoo small in the zooming and the attendant f stop adjustment the printedforeground image insert will have developed around its margins a lighthalo due to the mismatch of mattes. In very precise matte operationproduction of full color films some prior producers thereof haveresorted to the costly and tedious practice of using stop motionphotography for frequent checking of the effective sizes of matte coreareas and resizing thereof as demanded, while zooming progresses.

An ideal way of overcoming this problem, particularly in full colorproduction, is to vary the light intensity in some manner other than byconstant change of the f stop of the printing lens, but this should bedone in a manner to avoid altering the color temperature of the lightsource. For this purpose, some skilled in the art have resorted to theuse of a complicated filtering system embodying a variable densityneutral density disk. However, the making of such a variable neutraldensity filter disk in a suitable, precisely balanced form is verycomplicated and quite costly, and its operation in an effective mannerdemands unusually high skill.

Controlling and varying the light intensity by adjustment of the voltageof the electrical power supplied to a source of light rays, such asthatwhich energizes the filaments of incandescent lamp or lamps whenemployed as this source, imposes color change on its output. The higherthis voltage is the bluer the output beam becomes, and the lower thevalue to which this voltage is adjusted and redder is the production,but may be satisfactory for monochrome work, even through it iscomplicated and time consuming to attain with the precision required.

The use of neutral density filters to effect adjustments of the lightintensity is undesirable since they are inaccurate, difficult to producein fine enough steps of light intensity adjustment, very expensive toproduce and undesirably cumbersome.

When variable camera shutters are employed to adjust the light intensityyou inhibit the intent of its use for fades and dissolves.

Increasing the exposure time to increase the amount of light imposedupon the light sensitive material for recording a projected image, suchas a frame of the raw stock film, undesirably reduces the production oramount of footage output.

The present invention solves these problems of prior art practices in anunusual and economical manner which permits ready attainment of optimumperformances, and the automatic version thereof, hereinafter taught andclaimed, assures simple and rapid attainment of the desired results.

In the broadest aspect of the present invention projection opticalprinting apparatus is provided which may be employed for variableenlargement and reduction of a projected image to which light sensitivematerial is exposed. Such apparatus may be in the form of any of avariety of types of projection optical printers or in other apparatusemploying similar optical principles such as, for example, thosecommonly termed enlargers. The optical system of any such apparatuscomprises, in succession along the optical axis a light beam path, anapertured support for a film print that bears an image to be recordedwith this support extending in a print plane transversely of andsubstantially normal to the optical axis with the latter extendingsubstantially through the center of the support aperture, a printinglens substantially axially aligned with the optical axis, and atransversely extending support for light sensitive material through thecenter of which the optical axis extends and located at a plane ofprinting reproductions by the printing lens. It may embody suitablemechanism to translate along the optical axis one or more of theseunits, i.e., the light sensitive material support, the printing lens andthe film print support relative to the others thereof. An improved lightsource sub-assembly is embodied in such apparatus at a positionpreceding the film print support. This light source sub-assemblyincludes a source of light rays to which the light sensitive materialresponds for recording thereon a replica of the projected image, andmeans providing in a transverse plane an in-focus image of the lightsource preceding the film print plane, such as that at the location ofthe source of light rays or thereafter as may be effected by focusinglens means in a focal plane at the second principal focus of the latter.This light source sub-assembly also includes a mechanically adjustablelight valve in the light source image plane which embodieslight-blocking and masking transverse means having opposed edges locatedat substantially equal distances on opposite sides of the optical axisto define an intervening light-passing space. The portions of this lightvalve means which have the opposed edges are simultaneously movable bothdirectionally toward and away from the optical axis and in extent atequal increments of continuous motion for infinite variability of theintervening light-passing space.

An aspect of the improvement provided by the present invention involvesin a projection optical printer version thereof elimination of theseprior practices, so as to avoid the remarked problems attendant upon thepractice of such adjustments. This is accomplished preferably byproviding as the light source a sub-assembly which includes source oflight rays, e.g., the lamp or lamps in a lamphouse, a condenser ortransfer lens assembly having its first principal focus located at thelight rays source, such as the lamp filament or filaments, and adetermined focal length to a second principal focus thereof, and anadjustable light valve which is located in the remote transverse focalplane at the second principal focus of this condenser,

all axially aligned and fixed relative to each other along vided formoving these light valve vanes simultaneously in opposite directions inthe remote focal plane toward and away from the optical axis. Thesimultaneous motion of the opposed edges of these blades is in equalincrements of continuous motion for progressive approach toward andretrogressive retraction away from each other with substantialmaintenance of the equality of their spacings to opposite sides of theoptical axis for adjusting with infinite variation the intervening spaceto effect the required change in the quantity of light passestherethrough with maintenance of substantial equal distribution of thelight along this space. For practical service this adjustable lightvalve should be closely flanked on at least one side thereof by a fieldlens or collector, and preferably a pair of the latter closely flankopposite sides thereof for arbitrary balance. While one or more lampsequipped with filament means that are rendered incandescent byelectrical energization may be preferred as the source of light rays itis to be understood that other types of such sources may be used in thenew light source sub-assembly, such as fluorescent tubes and otherglowing gas devices. This unique light source sub-assembly projects animage of the energized source of the light rays to the remote focalplane. There is thus provided in this focal plane an in-focus image ofthe unmasked portions of the source of the light rays, e.g., theincandescent filaments, within the space intervening the opposed edgesof these vanes. As a result, the intensity of the light is adjusted bythe degree of the spacing between the opposed edges of the light valvevanes.

This improved light source sub-assembly is useful to great advantage ineven the simplest form of projection optical printers which includes, insuccession along the axis of the optical light beam path thereof andfollowing such light source sub-assembly, a transversely arrangedprojector head gate through the center of the aperture of which theoptical axis extends with a suitable field collector lens meansimmediately preceding this gate; a printing lens; and a transverselyarranged camera gate having a printing aperture to the center of whichthe optical axis extends. Such simple printer also conventionallyembodies film advancing means, e.g., interrnittents of the fixed pinregistration type, respectively associated with the projector gate andthe camera gate to guide and effect the translation of an image-bearingfilm strip past the former and the translation of a raw stock film strippast the latter, whereby successive frames of the raw stock film stripwill be printed with the images borne in the successive frames ofimage-bearing film strip.

By virtue of the use of this new light source sub-assembly in such asimple form of printer zoom shots may be embodied successfully insections of the printed raw stock film strip. As is conventional, theprinting lens and the camera gate, i.e., the camera framework whichcarries this gate, are translatable along the optical axis with theaxial translation by suitable follow-focus means of the camera and itsgate being correlated to but differing from the axial translation ofthis printing lens. For example, in accordance with prior art practice,on zooming in for blow up of printed images from a 1:1 ratio of thesizes of the projected images and the printed images to graduallyincreasing enlargement of the latter of, e.g., 1:3 the camera and itsgate are backed off progressively while the printing lens is advancedprogressively toward the projector gate; and on zooming out for gradualreduction of the sizes of the printed images to, e.g., 4:1, the printinglens and camera gate are both backed away with the lens progressivelyapproaching the raw stock at the camera gate. A full color productionwith the use of this simple form of printer (that is equipped with thepresent improved light source sub-assembly), involving zoom shots, isfree of undesirable color changes, and no f stop adjustments of an irisdiaphragm during the printing are required, since the desired alterationin the light intensity is effected by the present light valve that islocated remotely from the lamphouse. On zooming in for gradual blow upof the images being printed this light valve is gradually opened up forprogressively increasing the intensity of the light at the camera gateopening; and on zooming out for gradual reduction of the sizes of theimages being printed a progressively lesser quantity of light in thecamera gate opening is required, and thus the opening in this lightvalve is gradually made narrower for this latter operation.

The performance of projection optical printers which embody a pluralityof projection heads, including one or more aerial image projector heads,are likewise greatly improved by embodiment therein of the presentadjustable light source sub-assembly. Such improved performance may beconcerned with the operation thereof that relies on the use of blackcore and white core strip film mattes in assembling foreground imageswith background images of strip film prints, and the incorporationthereof in the negative strip film being printed of sections embodyingzoom shots. For this purpose the optical printer may embody a pair ofprojecting sections, and a single camera gate which is translatablealong the optical axis for zoom shots and with which is associated asingle such axially adjustable printing lens having its axialtranslation correlated to the camera gate translation for such purpose.One of these projecting sections is a primary projecting section thatincludes the new light source sub-assembly, i.e., the source of lightrays or lamphouse, the imaging transfer condenser and the new adjustablelight valve at the remote focal plane of the latter; an aerial imageprojector having its gate immediately preceded by a field collector lensmeans in an axially fixed position relative to this gate; common meansto support this new light source, the achromat and the aerial imageprojector head in fixed positions relative to each other along theoptical axis, but to effect adjustment thereof together along the latteras a unitary assembly; a master projector head fixed at a point alongthe optical axis and having its gate immediately preceded by anotherfield collector lens means in an axially fixed position relative to thislatter gate; and an axially and independently adjustable imagingtransfer lens inserted between these aerial image and master projectorheads for independent axial translation of this transfer lens relativeto this pair of projector heads. The other of this pair of projectingsections constitutes a secondary projecting section that is functionallysimilar to the primary projecting section and comprises similar opticalelements and associated supports and adjusting mechanisms from thestandpoint of purpose. This secondary projecting section has its opticalaxis directed toward and intercepted by the reflective face of anoblique light transmitting and reflective mirror means that isinterposed between the master projector head gate of the primaryprojecting secton and the camera printing lens with the optical axis ofthis primary section passing substantially centrally through this mirrormeans. It is preferred that the optical axes of this pair of projectingsections be arranged substantially normal to each other, i.e., at about90 with respect to each other. Each of the field collector lens meansmay be an achromat of suitable design.

The black core matte is translated transversely past the aerial imageprojector gate of the primary projecting section, the background imagebearing film is translated transversely past the master projector gateof this primary section, the white core matte is translated transverselypast the aerial image projector gate of the secondary projectingsection, and the foreground image bearing film is translated past themaster projector gate of this secondary section. Of course, the marginsof the foreground images which are to be inserted without overlap ormarginal gaps within the images of the background images upon the rawstock film being translated transversely past the camera gate during theprinting operation, and of the black core and white core areas of themattes which duplicate in size and shape those of the insert images willbe carefully matched initially to the latter by previously known orconventional techniques of preparing such mattes.

The adjustments of the spacing between the opposed edges of the vanes ofthe adjustable light valves embodied in the light source sub-assembliesof the pair of primary and secondary projecting sections is intended toand effectively will alter the effective intensities of the lightoutputs of the lamps. in the respective light source sub-assemblieswithin the limits of the demands for which the printer optical system isdesigned, in lieu of adjusting an iris diaphragm in the printing lensassembly for this purpose. The effective sizes of the black core andwhite core simulations of the foreground inserts in relation to those ofthe latter are readily maintained even during blowup and reduction zoomshots within the extremely small limit of variations permitted forattainment of optimum results. The employment of the new light valvesand the light source sub-assemblies embodying them assures that, oncethe mattes have been correctly matched to each other and to theforeground image inserts, the critical matching will be maintainedregardless of whether or not a camera zoom is imposed.

Apart from the great advantage attained by the use of the improvedadjustable light source sub-assembly of the present invention (whichincludes the present adjustable light valve remote from the source ofthe light rays) in a plural projection head optical printer in theassembling of a plurality of images, such as foreground and backgroundimages, in the frames of the raw stock film being printed with the useof properly sized black core and white core mattes, is the furtheradvantage of assuring reliable attainment of a more subtle capability ofaccuracy and of repeatability of the desired results. In printingoperations performed by a highly skilled operator with the use of priorprojection optical printers in which required changes of light intensityare attained by adjustment of the iris diaphragm in the printing lens heusually can do no better than attain a degree of accuracy of aboutone-eight of an f stop even with the exercise of the greatest of care.By comparison, when he performs a similar printing operation with theuse of a projection optical printer of the present invention he canattain with assured reliability a degree of accuracy of aboutone-twenty-fourth to one-thirtieth (1/24 to 1/30) of an f stop, which isconsiderably greater than the presently accepted maximum degree ofaccuracy of one-twelfth 1/12) of an f stop.

Since the effective light intensities or the outputs of the lamphousesare controlled by the new light valves of the present invention theoutputs of the lamps readily can be maintained at the correct colortemperatures and the printing lens can be constantly maintained at itsbest f stop, to allow production of full zooms with no deleteriouschanges in image sizes.

As to the essential maintenance of balance or matching of the colortemperatures of the lamps in a printer employing a plurality ofprojecting sections, and thus a plurality of light sources, it must berealized that lamp manufacturers are incapable of maintaining in aneconomical manner production control which will assure the same colortemperature for a plurality of the lamps that they produce. Further, asthe life of use of a lamp progresses color temperature change thereofoccurs. This balance is maintained in plural projecting sectionsversions of the projection optical printers of the present invention byassociating advantageously with the light output opening of each sourceof light rays, e.g., lamphouse, a swingable dichroic color correctingfilter preceding the imaging or light transfer condenser of this newlight source sub-assembly. Change of the angle of incidence of suchswingable filter with respect to the optical path of the output beamwill permit such color correction as will assure identical performancesof the lamphouse light sources.

it is also desirable to remove from the optical system the heat raysemanating from the light source beam at a point in the light sourcesub-assembly, preceding the light valve and its one or more flankingfield lenses. This is efficiently accomplished by interposing betweenthe imaging transfer condenser and the field lens which flanks theapproach side of the light valve, or the latter if a single flankingfield lens is employed on the exit side of the light valve, a dichroicmirror arranged obliquely to the optical axis extending therebeyondsuccessively through the light valve and the succeeding projector head.This dichroic mirror will turn the light path through an angle, e.g.,about This will perform two desirable functions, i.e., (l) to passtherethrough out of the optical system undesirable heat rays, and (2) toturnthe optical axis through an angle of less than which places to oneside the source of light rays or lamphouse and, if desired, theoperative mechanism associated with the light valve to manipulate thevanes thereof for adjusting the intervening space between the opposededges of the light valve vanes. As a result of the second function theoverall length of the printer may be desirably shortened and theelements of the system preceding this oblique dichroic mirror, may beoffset to one side so as to make the printer structure more compact andto move the offset structure and elements to one side out of the way.

It may be further desirable to mount in the projecting section of eitherthe simple single projection head version of the printer at a pointpreceding the field collector lens means or achromat associated with thelatter, or in the version embodying a plurality of projector headsincluding an aerial image projector head immediately preceding the fieldcollector lens or achromat associated with the latter, a transverselyarranged diffuser in the form of a plano translucent sheet having afinely ground surface. In such printer embodiments such diffuser is thuslocated beyond the light source sub-assembly or the improved light valveof the present invention and its one or more flanking field lenses. Suchdifl user will desirably break up the light rays between the image ofthe energized source of light rays or incandescent lamp filamentstransmitted to the remote focal plane in which the light valve vanes arearranged and the field collector lens means or achromat locatedtherebeyond, so as to assure in the light beam a rather uniform densityof field of illumination.

The means for manipulating both of the opposed light valve vanes of theimproved light valve which is embodied in the light source sub-assemblymay be provided in a variety of forms. In any case, the opposed edges ofthe light valve vanes are to be moved simultaneously in continuousmotion either toward or away from each other. This is particularlyadvantageous when an automatic system is provided to effect suchadjustment in response to signals developed by translation of the cameragate along the optical axis, translation of the transfer lens along theoptical axis when it is interposed between an aerial image projectorhead and a relatively fixed projector head in a projecting section of aplural projector head version of the printer, and an operator adjustabledevice or manual controller which creates a third signal. The meanswhich moves one or more of the light valve vanes relative to the otherfor adjusting the intervening light passing space therebetween maycomprise a driven rotary cam structure provided with a contouredcircumambient track (which may extend through more than 180) andfollower means urged to continuous contact of the latter. The means torotate this cam is such that it will rotatably translate its track in amanner whereby the advancing point of contact thereof by the followermeans progresses linearly in radial degrees, in order to obtain a squareoutput from the cam and its follower means, and manipulating mechanismconnecting the latter to the light valve vanes for manipulating them.

For the latter purpose the light valve may include a symmetricalparallelogram mechanism which comprises a pair of opposed andsubstantially parallel side bar members and substantially parallel endbar members that are spaced apart in the direction of the longitudinaldimension of the side bar members and which are pivotally connected atlongitudinally spaced points to the latter. As a result, rotation of oneof these end bar members of the parallelogram mechanism by the camfollower means in one direction causes the side bar membersprogressively to approach each other, and when this end member isrotated in the opposite direction it causes them retrogressively toretract from each other. The side bar members of the parallelogrammechanism respectively carry one of the light valve vanes so as toeffect simultaneous motion of the pair of the latter for advancing andretracting their opposed edges toward and away from each other.

Such light valve manipulating mechanism and the system in which it isembodied may include to advantage an operator-adjustable selector lightcontrol or manual controller for imposing on this system a signal foraccommodating situations where the light changes for any givenenlargement or blowup and for any given reduction exceed the potentialof the light valves. For example, the maximum light required for acertain operation may be greater than that available when the lightvalve in the concerned projecting section is wide open. In such case thelight valve is closed down partially by the selector light control andthe camera shutter speed is decreased until the net result of thequantity of the illumination at the printing aperture or camera gateopening is equivalent to that required for this particular operation. Itmay also provide other advantageous services.

The automatic control of the adjustment of the improved light valve ofthe present invention includes position control means which areoperatively connected to the axially translatable printing lens andcamera gate on one hand and to the movable light valve vanes on theother hand. As a result, the vanes automatically are movedproportionally with respect to the axial translation of the printinglens and camera. For this purpose there may be coupled to the mechanismfor axially translating the printing lens and camera gate in correlatedmanner, e.g., the drive of follow-focus mechanism, a signal generator,e.g., a potentiometer, which is continuously manipulated automaticallyby and in pace with the operation of such mechanical drive. Thismanipulation of the potentiometer causes the latter to develop anddeliver an output signal that is proportional to the printing lens andcamera gate axial translation and is supplied by suitable controlcircuitry or circuit means to a servomotor which in turn, throughsuitable drive mechanism, such as gearing and cam means and vanemanipulating mechanism, physically adjusts the light vanes relative toeach other. Desirably, the servomotor output drive is suitably coupledto another signal generator or potentiometer to develop and deliveranother output signal which is proportional to the mechanically drivenvane motion. These two signals are supplied in opposition to each otherto an electrical combining or summing means in the control circuitrywhich may be a suitable amplifier with an input network adapted toperform this function, so as to produce a resultant circuit outputsignal to which the servomotor responds for controlled operation of thedrive mechanism that manipulates the light valve vanes to adjust thewidth of the light-passing slot between the latter. In order to permitthe person who is operating the printer to adjust the range of theopening of the light valve which is then to respond to automaticcontrol, i.e., the light-passing space between the opposed edges of thepair of vanes thereof, there is also provided the previously indicatedmanual controller or selector light control that is coupled to a thirdsignal generator or potentiometer for manual manipulation to develop anddeliver still another output signal that is proportional to thecontroller setting. This third output signal is combined or summed inthe control circuitry with the other two output signals to produce theresultant circuit output signal that controls the drive of servomotor.All of these transducer elements may be embodied in the-automaticcontrol means connected between the camera translating drive mechanismand the light valve vane adjusting mechanism as the interposed controlmeans.

When such an automatic control system is embodied in a plural projectorhead projection optical printer with one projecting section thereofcomprising, in succession along its optical axis, the improved lightsource sub-assembly, an aerial image projector head with its fieldcollector lens means or achromat immediately preceding the gate of thelatter, an imaging transfer lens, and a relatively fixed masterprojector head, the light source sub-assembly and the aerial imageprojector head with its immediately preceding field collector lens meansor achromat may be advantageously supported by common means which istranslatable as an assembly unit along the optical axis. This latteraxial translation feature requires that the imaging transfer lens whichis interposed between the gates of the aerial image and master projectorheads be independently supported and translatable along the optical axisto keep in focus at the master projector gate images that are projectedfrom the axially translatable aerial image projector gate. Accordingly,when the automatic control system is embodied in such a printer a fourthsignal generator or potentiometer must be coupled to this imagingtransfer lens so that the output signal from this generator is suppliedto the summing network of the combining circuitry to create theresultant circuit output signal that controls the drive of theservomotor.

The objects of the present invention which have been made apparent fromthe preceding discussion of the problems entailed by prior art printingprocedures and the known printers to perform them, as well as thetherefollowing resume of the constructions and desirable operations ofthe various embodiments of the present projection optical printer, aresupplemented by other objects which will in part appear from referenceto the following detailed description taken in connection with theaccompanying drawings, wherein like numerals identify similarpartsthroughout, and in which:

FIG. 1 is a diagrammatic view of the optical system of an embodiment ofa projection optical printer of the present invention in simple formwhich includes a single projector head and the improved light sourcesubassembly thereof;

FIG. 1A is an elevational view of the exit side of the vanes of thelight valve embodied in the light source sub-assembly of FIG. 1, withparts broken away, illustrating the image of the energized light rayssource intervening the separated edges of the vanes thereof;

FIG. 1B is an enlarged side elevational view, with parts broken away, ofa camera structure and the camera or printing lens which is associatedtherewith, as well as of a suitable mechanism for translating theprinting lens along the optical axis of the printer and conventionalencased follow-focus mechanism for translating the camera and its gatealong-the optical axis in correlation to the translation of the printinglens;

FIG. 2 is a diagrammatic view similar to FIG. 1 of the optical system ofanother embodiment of the projection optical printer which hasincorporated therein the improved light source sub-assembly of thepresent invention and other desirable features thereof, this embodimentbeing characterized by a pair of projector heads and their associatedgates with one constituting an aerial image projector head and the otherconstituting the master projector head;

FIG. 3 is a diagrammatic view similar to FIGS. 1 and 2 of the opticalsystem of still another embodiment of the projection optical printerwhich includesthe projecting section of FIG. 2 as a primary projectingsection and a similar projecting section as a secondary projectingsection which is incorporated in the optical system by an oblique lighttransmitting and reflective mirror means interposed between andoptically aligned with the primary projecting system and the printinglens;

FIG. 4 is an enlarged elevational view, with parts broken away and insection, of mechanism of the improved light valve which may be embodiedto advantage in the printers and optical systems thereof that areillustrated in FIGS. 1 to 3 incl.;

FIG. 5 is another side elevational view, with parts broken away and insection, of the structure shown in FIG. 4 and as viewed from a positionat to the plane of observation of the structure shown in FIG. 4;

FIG. 6 is a further enlarged sectional view, with parts in elevation,taken substantially on line 6-6 of FIG. 5; FIG. 7 is a perspective view,with parts broken away and in section, of structure and optical elementsof the projection optical printer that embodies the projecting system ofFIG. 3, illustrating parts and elements of an automatic control system;

FIG. 8 is a block diagram of the automatic control or servo motor systemembodied in the printer illustrated in FIG. 7;

FIG. 9 is an elevational view of the exit side of another embodiment ofthe light valve, with parts broken away, which will perform the samelight intensity adjustment as is attained by that of FIGS. 4, 5 and 6;and

FIG. 9A is an end elevational view of one of the light valve vanes andits operating means that are illustrated in FIG. 9.

In the optical system of the projection optical printing apparatus,which is diagrammatically illustrated in FIG. 1 as being a simpleversion of a projection optical printer, by way of example, thereference numeral 10 identifies the projector" section thereof and thereference numeral 11 identifies the camera section thereof. The opticalsystem of FIG. 1 has embodied therein an improved light sourcesub-assembly of the present invention. I

This light source sub-assembly comprises, in succession along theoptical axis, a source of light rays, such as the filaments 112 of anincandescent lamp l2, and a curvilinear reflector 13 located on the backside thereof (as representative of light source elements housed in aconventional lamphouse), a condenser or transfer lens assembly 14 and anadjustable light valve 15 in the remote focal plane at the secondprincipal focus of this condenser for projecting an in-focus image ofthe hot filaments of the lamp 12 to this focal plane. This light sourcesub-assembly also includes at least one field lens or collector 16closely flanking one side of the focal plane in which vanes of the lightvalve 15 are located. Preferably, for arbitrary balance, a pair of thefield lenses or collectors 16 are provided which closely flank oppositesides of this focal plane.

The light valve includes a pair of blades or vanes 17 and 18, which arelocated in the remote focal plane at the second principal focus of thecondenser 14, that respectively may have to advantage opposed straightline edges 19 and 20 defining therebetween a lightpassing slot ofsubstantially uniform width from side to side. The beam comprising abundle of light rays which is passed through the slot intervening theopposed vane edges 19 and 20 is margined by the full lines shown inFIG. 1. When a greater quantity of light at the camera gate opening isdemanded for obtaining the desired printing results for any particularsection of the series of images borne by the image bearing film beingtranslated past the projector head gate 21 the light valve 15 is to beopened up as required, i.e., by separating the opposed vane edges 19 and20, to increase the width of the slot intervening them.

When the source of light rays, e.g., the filaments 112 r of incandescentlamp 12, is energized the bundle of light rays or beam emanatingtherefrom which exit through a directive hole in the enclosinglamphouse, pass through the condenser 14 to be focused at the focalplane location of the light-passing slot intervening the opposed andspaced apart edges 19 and 20 of the light valve vanes 17 and 18. Thus,in this focal plane is produced an image of the energized and glowingsource of light rays 112. This image can there be observed as appearingto be an exact duplicate of at least a medial portion of that which isseen if one looks directly at the energized lamp 12. An unmasked medialportion of this projected image of the source of light rays appears inthe slot or space intervening the separated light valve vane edges 19and 20, such as that illustrated in dotted lines at 112-I in FIG. 1A,with marginal rays of the projected bundle of rays or beam being blockedout or stopped beyond these vane edges by the blocking and maskingportions of the vanes 17 and 18 outward of their opposed edges.

The FIG. 1 printer optical system also includes as an essential part ofthe projector a projector head equipped with a transversely-arrangedgate 21 having a gate opening or aperture 22 past which is translatedframe-by-frame along a transverse path (by suitable film advancingmeans, not shown) an image bearing strip film 23 for projection from thesuccessive frames thereof of the images borne thereby. The projectorhead gate 21 is immediately preceded by a field collector achromat 24which is located as close thereto as is permitted by structurallimitations. Although it is not necessary to broader aspects of thepresent invention, it may be desirable to interpose between theadjustable light valve and any field lens 16 flanking the output sidethereof on one hand and the projector head gate 21 on the other hand adiffuser 25 in the form of plane transherent sheet having a finelyroughened or ground surface to break up and tend to evenly distributethe light rays being passed therethrough.

The camera assembly 1 1 of the printer optical system of FIG. 1 alsoincludes a camera or printing lens 26 and a framework supporting atransversely arranged camera gate 27 which is translatable along theoptical axis by suitable mechanism. The camera gate 27 is provided witha printing opening or aperture 28 past which a raw stock strip film 29is to be translated frame-byframe (by any suitable film advancing means,not shown) for exposure of successive frames thereof to the images beingprojected from the successive frames of the image bearing film 23.

In a conventional manner, the printing lens 26 and the camera gate 28are translatable along the optical axis with the axial translation ofthe camera framework and its gate 28 being correlated by suitablemechanism to, but differing from the axial translation of the printinglens, for the purpose of permitting the production of blow-up andreduction shots in sections of the raw stock film 29 being printed. Inaccordance with standard practice in this art, on zooming in for blow upof printed images from a 1:1 ratio of the sizes of the projected imagesand the printed images to gradually increasing enlargement of the latterof, e.g., 1:3, the camera 11 and its gate 27 are backed offprogressively while the printing lens 26 is advanced progressivelytoward the projector gate 21. In accordance with this practice, onzooming out for gradual reduction of the sizes to, e.g., 4:], theprinting lens 26 and the camera with its gate 27 are both backed awaywith this lens progressively approaching the raw stock at the cameragate. Thus the camera framework and the gate 27 thereof are as farforward as they will ever be during printing operations at a 1:1 ratioof projected images at the projector gate 21 and the images beingprinted at the camera gate 27. Mechanism for performing this adjustmentautomatically of the printing lens 26 relative to the camera gate 27 isfamiliar to those skilled in the art as a follow-focus or mechanicalauto focus and thus no details thereof are shown herein, such mechanismbeing represented diagrammatically at 30 in FIG. 1 with lines connectingit respectively to this camera gate and printing lens. As a result, anysuitable driving means which may include an electrical motor, will causethe follow-focus mechanism 30 automatically to adjust progressively,along the optical axis translation of the camera gate 27 relative to thetranslation therealong of the printing lens 26.

FIG. 18 indicates that an externally threaded section 32 of a driveshaft 33 that is rotated by suitable motive means, such as an electricmotor 34, may extend through casing 36 of a follow-focus mechanism 30,with its forward end 35 projecting therebeyond. Within this follow-focuscasing 36 a nut may be fixedly carried by bracket 37 which supports theprinting lens 26, with threaded shaft section 32 threadably engagedtherethrough progressively to translate the printing lens forward towardthe projector head, upon rotation of the shaft 33 in one direction, andsimultaneously progressively to retract the camera gate 27 awaytherefrom to attain progressive blow up of the images being printed.This zooming in action begins from the relative positions of theprinting lens 26 and camera gate 27 where the ratio of the images at theprojector gate 21 and those projected to the camera gate for printing is1:1. From such start positions of the printing lens 26 and camera gate27 zooming out action may be progressively accomplished by rotating thedrive shaft 33 in the opposite direction threadably to retract theprinting lens 26 and the camera framework with its gate 27simultaneously with the printing lens progressively approaching thecamera gate. Such differential actions of the camera gate 27 areautomatically accomplished by the follow-focus mechanism of knownconstruction and operation which is housed in the casing 36. In ac- Icordance with standard practice the back end of the lens 26 is connectedin light excluding fashion to the front end of the camera 11 by theusual bellows indicated in broken lines at 38.

Suitable independent mechanisms may be provided for axially translatingthe printing lens 26 with automatic follow focus adjustment of thecamera 11 with its gate 27 therewith, and for simultaneously adjustingthe opposed light valve vanes 17 and 18 at will and under the control ofthe skilled person operating the printer simultaneously in response tothe correlated axial translation of the printing lens 26 and camera gate27. As will be more fully understood in connection with FIGS. 3, 7, and8 such automatic adjusting or control means may require an electromechanical transducer, e. g., a signal generating-unit which responds tothe correlated axial translation of the printing lens 26 and camera 11for automatically dictating the adjustment of the width of the slotbetween the opposed edges 19 and 20 of the light valve vanes 17 and 18.For this purpose the drive shaft 33 may be provided at any suitablepoint, such as that indicated at 39, with a driving take off foroperating such signal generating unit.

' As is indicated in the diagrammatic optical system of FIG. I 2 amodified form of the projection optical printer, which is improved inaccordance with the teachings of the present invention, may embody theessential optical elements and equipment of FIGS. 1, 1A and 1B and, inaddition, a plurality of projector heads, such as for the purpose taughtin the identified Oxberry US. Pat. No. 3,040,619. In the optical systemof FIG. 2 there is added to the projector section of the printer anadditional projector head equipped with a transverselyarranged gate 121having an aperture or opening 122 past which is to be translated (bysuitable film advancing means, not shown) a strip film matte as istaught in the identified Oxberry US. Pat. No. 3,040,619. This gate 121is that of an aerial image projector head, and it is immediatelyprecededby an additional field collector achromat 124, which may be similar tothat at 24, suitably supported on this aerial image projector head.

Since images borne by the successive frames of the strip film matte 123are to be projected in focus to the plane of the image bearing film 23being translated across the aperture or opening of the master projectorhead gate 21 there is interposed between the gates of these twoprojectors an imaging transfer lens assembly 40. This lens assembly 40is independently translatable along the optical axis for maintaining infocus at the master projector head gate 21 the matte images which areprojected to the latter thereby, and any suitable means under thecontrol of the person doing the printing may be provided foraccomplishing this independent translation.

The printer optical system of FIG. 2 is equipped with the previouslydescribed light source sub-assembly ineluding, e.g., the light rayssource lamp 12 (inclusive of its energized filaments 112), the condenseror transfer lens assembly 14, and the adjustable light valve with itsflanking field lenses 16. For purposes of conserving space, but moreimportantly for removing from the optical system the heat rays of thelight beam being projected from the lamp 12 toward the focal plane wherethe adjustable light valve 15 is located, an obliquely oriented dichroicmirror 41 may be inserted in this light source sub-assembly between thecondenser 14 and the light valve 15, preceding any field lens 16associated with the latter, for turning the optical axis of this lightsource sub-assembly through an angle of less than 180, such as Thisdichroic mirror 41 alternatively may be inserted in the optical systemimmediately following the light valve 15 and its forward flanking fieldlens 16 t at a point preceding the diffuser 25. This dichroic mirrorwill reflect forward from its incident face the light rays for passageof a bundle thereof through the succeeding optical elements of theoptical system. When this dichroic mirror is located at a pointpreceding the light valve 15 the bundle of reflected rays passsuccessively through the open slot of this light valve, the aerial imageprojector head achromat 124, the gate 121 of this head, the imagingtransfer lens assembly 40, the achromat 24 of the master projector headand the gate 21 of the latter. A large proportion of the heat rays whichare embodied in the bundle of light rays or beam emanating from theincandescent lamp filaments 112 will be transmitted through the obliquedichroic mirror 41 for desirable dissipation thereof out of the opticalsystem, and to avoid undesirable heating of the optical elementstherefollowing, such as the diffuser 25 Since in such a plural projectorhead system of the type illustrated in FIG. '2 it is desirable that theaerial image projector head which includes the gate 121 and themechanism associated therewith to translate the matte strip film 123across the opening 122 of the latter, as well as the achromat 124closely associated with this gate, be translatable together along theoptical axis, this aerial image projector head also supports thedescribed light source subassembly. In other words, common means supportin succession at fixed positions relative to each other along theoptical axis this light source sub-assembly, the additional achromat 124and the aerial image projector gate 121 with this common means beingadjustably translatable along the optical axis by any suitable meanswhich may be under the control of the person operating the printer. Forthis reason the imaging transfer lens 40 is independently translatablealong the optical axis.

It is indicated in FIG. 2 that there may be interposed in the lightsource sub-assembly, between the lamp 12 and the condenser or transferlens assembly 14 a color correcting dichroic filter 42, which desirablymay be made of glass. The filter 42 is swingably mounted so that theangle of incidence thereof with respect to the optical path projectingfrom the exit opening of the lamphouse, in which the light source lamp12 is housed, may be changed as may be required in order to maintainconstant the color temperature of this light source. As will be madeapparent later this can be important with respect to maintainingidenticalness of the color temperatures of the light sources of a pairof the projecting sections when embodied in a sophisticated version ofthe projection optical printer for the purpose of full color printinguse thereof.

In FIG. 3 is illustrated the optical system of such a sophisticatedprojection optical printer which embodies a pair of the projectingsections, in association with a single printing lens and camera section.It will be seen that a primary projecting section of the optical systemof FIG. 3 and the camera and printing lens assembly associated therewithare substantially like that illustrated in FIG. 2. There is added to thelatter a secondary projecting section which is similar to the primaryprojecting section and the optical axis of this secondary projectingsection is directed toward and intercepted by the oblique reflectiveinterface 43 of a light transmitting and reflective mirror means, whichmay be in the form of a cubic beam splitter 44 formed by a pair of rightangle prisms cemented together along the oblique plane constituting thereflective interface. This beam splitter 44 is inserted in the opticalsystem of FIG. 2 b interposing it between the printing lens 26 and thegate 21 of the master projector head.

Thus this secondary projecting section of the FIG. 3 printer opticalsystem includes the improved light source sub-assembly, an aerial imageprojector head gate and a master projector head gate with each having anachromat closely associated therewith, and an independently axiallyadjustable transfer lens assembly interposed therebetween, with theoptical axis of this secondary projecting section directed to the centerof the oblique reflecting interface 43 through which the optical axis ofthe primary projecting section extends to the center of the printinglens 26. In other words, this secondary projecting section comprises, insuccession along the optical axis thereof, a light source lamp 212, aswingable dichroic filter 242, a condenser or transfer lens assembly214, an oblique dichroic mirror 241, an adjustable light valve 215 withits flanking field lenses 216, an aerial image projector head gate 321with its associated achromat 324, an imaging transfer lens 240, and amaster projector head gate 221 with its associated achromat 224.

This optical system of the sophisticated projection optical printer,characterized by four projection heads with a pair thereof respectivelyembodied in a primary projecting section and in a secondary projectingsection, as is illustrated in FIG. 3, is designed, e.g., for assemblingduring the printing procedure in the frames of the camera raw stockstrip film 29 images of a background scene and image inserts of aforeground subject. Thus the film strip 23 which is translated acrossthe aperture or opening 22 of the master projector head gate 21 of theprimary projecting section may carry in successive frames thereof imagesof the desired background. A strip film 123 in the form of a black corematte will be translated across the a nrture or opening 122 of theaerial image projector gate 121 in the primary projecting section. Also,the film strip 223 which is translated across the aperture or opening222 of the master projector head gate 221 of the secondary projectingsection will bear foreground images which include the desired insertimages that are to be superposed on the background images projected fromthe strip film 23 to the camera raw stock strip film 29. Further, awhite core matte strip film 323 is translated across the aperture oropening 322 of the aerial image projector head gate 321 of the secondaryprojecting section.

Let it be assumed, for purposes of illustration, that the backgroundimages carried in the successive frames of the strip film 23 which istranslated, frame-by-frame,

past the apertured gate 21 of the master projector head in the primaryprojecting section are those of a hilltop landscape. It may be desiredthat there be inserted in the frames of the camera raw stock strip film29 foreground images surrounded by images of the background landscape,to give the impression that a foreground subject, such as a lady withwindblown hair, which were printed in successive frames of theforeground image bearing film 223 that is being translated past theapertured master projector gate 221 of the secondary projecting section,were photographed at the site of the hilltop landscape rather than in astudio. In accordance with technique conventional to the projectionoptical printer art, the black core matte film 123 is prepared so thatin the successive frames thereof areas which are the exact duplicates insize and shape of the desired foreground image insert, that are in thesame aspects frame-to-frame with respect to the latter, are opaqued andsurrounded by image-free, transparent fields. In accordance with thisknown technique, the white core matte film 323 bears in each of itssuccessive frames a transparent area which exactly matches respectivelythe desired foreground image insert and the black core opaqued areas ofthe corresponding frarnes of the foreground image film 223 and blackcore matte 123, with these transparent duplicates of the desiredforeground image inserts being surrounded by an opaque field.Accordingly, the black core matte 123 successively will blank out of thebackground images being projected from the successive frames of thebackground image bearing film 23 areas which are duplicates of thedesired foreground inserts for projection into these blank areas imagesof the desired foreground inserts. The white core areas of the matte 323will match up with the desired foreground image inserts of theforeground image bearing film 223 for projection thereof into the blankareas of the background images at the beam splitter transmitting andreflective interface 43, while the opaqued field of the white core mattewill prevent rays from passing forward through the surrounding fieldareas of the successive frames of the foreground image film 223 forpreventing any overlay upon the desired background image field areasbeing projected from the background image bearing film 23. The assembledbackground and foreground images for successive frames are thentransmitted forward from the beam splitter 44 through the printing lens26 for printing thereof together upon the successive frames of thecamera raw stock film 29.

It will thus be seen that the opaqued core areas of the black core matte123 and the transparent areas of the white core matte 323 must be keptexactly matched from frame-to-frame to the foreground image insertsthroughout the printing procedure, including any zooming for blowup orreduction in any sections of the camera raw stock film 29 being printed.This printing procedure thus requires extremely accurate adjustments ofthe light intensities being delivered from the respective sources oflight rays or lamphouses 12 and 212 of the primary and secondaryprojecting sections, and the desired balance of the lighting of thebackground image fields and foreground image inserts must be maintainedthroughout the printing procedures with adjustments thereof as may berequired to attain this end.

These accurate adjustments of the light intensities from both lightsources of the primary and secondary projecting sections is attained byadjustments of the slot openings in the light valves and 215, as may bedictated by the skill of the person operating the printer. The practiceof his skill is guided by a camera composing projection viewer which maycomprise a mirror 141 preceded by a collector 116, and a projecting lens45 so related to the camera gate opening 28 as to project upon a viewingscreen 46 the composite images as assembled at the camera gate opening,so that the printer operator may check his composition before exposingany of the raw stock film. Since the adjustments of the intensities ofthe pair of light beams being projected respectively from the primaryand secondary projecting sections is attained by the improved lightvalves 15 and 215 there is no need for a change of the f stop of theprinting or camera lens 26. Consequently, the desired maintenance ofexact matching of the margins of the foreground image inserts with themargins of the blanked out cores of the background images in which suchinserts are assembled is attained, so as to avoid efficiently thedevelopment and appearance in the images assembled in the successiveframes of the camera film being printed any black marginal lines orlight halos along the margins of the insert images of the lady with theflowing hair.

When, in accordance with prior printing technique, change of the f stopof the printing lens is employed to adjust light intensity during zoomshots the attendant change in the sizes of the images cannot be avoidedwithout practice of stop motion photography so that the cores of themattes can be checked with respect to the insert images and resized asthe zooms progress. In the case of the insert images being in the formof a subjectss upper torso and head with flowing hair, for example, thedevelopment of black line halo along bulk areas, such as her face,presents a problem of elimination many times less than that of thedevelopment of the black halo lines along minute structural details,such as the strands of the flowing hair. Despite the fact that criticalmatching may be initially attained at the beginning of the zoom shotsthe progression of the latter, with attendant required adjustment of thelight intensities by means of f stop adjustments of the printing lens,develops such black line halos which are most apparent along the marginsof the smaller insert image elements, such as the strands of the ladyshair, when such camera film is exhibited. This is a difficulty which isso easily eliminated by the present improvement of the optical system ofprinters by incorporation therein of the new light source sub-assembliesfeaturing the adjustable light valves of the present invention whicheffeet the desired changes in light intensities to a critical andcommercially acceptable standard.

The incorporation of the swingable color correcting dichroic filters 42and 242 at the light exit openings of the lamphouses in which the lampsl2 and 212 are respectively mounted provides an easy method formaintaining the color temperatures of the two separate light sourcesidentical for full color printing. The two separate light sources are tobe controlled independently since the beam splitter 44 reduces thequantities of light transmitted therethrough from different directions.

It will be noted from FIG. 1 that all of the optical elements of theprojector section 10 of the simplest type of printer are located atrelatively fixed points along the optical axis, while the position ofthe camera 11 is adjustable therealong, as is indicated by thedouble-ended arrow 50. It is also indicated by the double-ended arrow 51in FIG. 1 that the printing lens 26 is also adjusted along this opticalaxis. As has been previously indicated, this axial adjustment of theprinting lens and camera frame, i.e., the gate of the latter, the axialtranslation of the camera and its printing gate 27 being correlated tothe translation of the printing lens by means of the follow-focusmechanism 30 to realize the results of follow-focus practice previouslydeveloped in this art.

In the aerial image projection optical printer, the optical system ofwhich has been diagrammatically shown in FIG. 2, while the masterprojector head gate 21 and the achromat 24 associated therewith haverelatively fixed positions along the optical axis the light sourcesub-assembly and the aerial image projector gate 121 and the achromat124 associated with the latter are all adjustable along the optical axis(Z) as a unitary assembly, as is indicated by the double-ended arrow 52.The imaging transfer lens assembly 40 is likewise and independentlyadjustable along the optical axis (Z) as is indicated by thedouble-ended arrow 53. The doubleended arrows 50 and 51 respectivelyindicate correlated adjustability of the camera printing gate 27 and theprinting lens 26 along the optical axis (Z).

In FIGS. 4, 5, and 6 are illustrated mechanisms for manipulating thepair of opposed vanes of the light valve 15. This is in the form of ahoused assembly 55 in which is fixedly supported an upright partition 56on the back side of which, as viewed in FIG. 4, is supported by suitableposts 57 (FIG. 5) a gear box and clutch assembly casing 58. This gearbox and clutch assembly casing 58 in turn supports a high speedservomotor housing 59 and a three revolution potentiometer or nullingpotentiometer housing 60. The servomotor is a reversible one of knownconstruction and characteristics. As is known in the art, the clutch andgear box 58 contains a drive gear which is fixed on the motor shaftextending therethrough and this gear constitutes the first one of aspeed reducing train. The last gear of this speed reducing train ofgears is carried by a slip clutch mounted on the nulling potentiometer,the end of which extends out of the bottom of this casing beingindicated at 61 in FIG. 5. Consequently, after three revolutions of thenulling potentiometer shaft 61, check means provided in this over-alllight valve vane driving mechanism dictates stop thereof and causes thisshaft to be stopped with the slip clutch permitting any overdrive orcontinued rotation of the servomotor shaft that may occur.

A pinion 62 is mounted on the extending end of the nulling potentiometershaft 61 and is fixed thereto by a clamp 63 for drive thereby when theclamp is tightened. A larger gear 64 is mounted on and fixed to abearing-supported shaft 65 with its supporting bearing unit 66 mountedin a hole extending through the partition plate 56. Beyond the partitionplate 56 the head of the shaft 65 carries ring and cap clamping means 67which fixes thereto a segmental plate 68 for rotation thereby. Bearingunit 66 supports for swing thereon of a radially projecting arm 69 withthe end thereof extending beyond the circumference of the gear 64, as isbest seen in FIG. 4. A pair of pins 70 and 71, which are actuallyseparated and fixedly carried by partition plate 56, are located in thepath of the projecting end of the arm 69 for limiting the swing of thelatter through an arc to, e.g., about 28 to 30. A pin 72, fixed on thegear 64, projects into the path of the radial arm 69 for engagementthereby. Thus, the gear 64 is limited in rotation in one direction byabutment of the projecting end of the arm 69 against the fixed pin 70and contact of the gear-supported pin 72 against the opposite side ofthis am, and a reverse rotation of this gear is limited by engagement ofthe projecting end of this arm back against the fixed pin 71 and thereverse rotation of the gear-carried pin 72 through almost a completerevolution until this gear-carried pin engages against the opposite sideof this arm. Gear 64 is thus limited to a rotation in oppositedirections through an arc of an extent up to approximately onerevolution thereof. Consequently, the smaller drive pinion 62 which ismeshed with the gear 64 is limited in rotation to the three turns of thenulling potentiometer shaft 61 that is permitted by the construction ofthis nulling potentiometer, since an overrun of more than three turnswould damage the latter. It is this stop device which causes the nullingpotentiometer shaft 61 to stop while the servomotor,

housed at 59, may continue to overrun with this being accomodated by theslip clutch drive between the reduction gearing mounted to the motorshaft and the slip clutch mounted upon the nulling potentiometer shaft.

A cam 73, best seen in FIG. 6, is fixed to the shaft 65 by the segmentalplate 68 and a plurality of screws 74 which fix this cam and platetogether. Accordingly, the cam 73 is rotated by the gear shaft 65, inthe clockwise direction as viewed in FIG. 6. As is therein indicated cam73 is provided peripherally with a cam track 75 which is contouredthrough an appreciable portion of a full turn. A suitable cam follower76, preferably in the form of a roller, is carried by a segmental arm orplate 77 which is pivotally supported at 78 (FIG. 6) by a pivot shaft 79in turn rotatably supported by a bearing 80 mounted through thepartition plate 56 (FIG. A biasing tension spring 81 is fixed at onepoint 82 to the pivoted follower arm 77 and at another point 83 to thepartition plate 56, so as to tend to urge this pivoted follower platerotationally in a clockwise direction, as viewed in FIG. 6, for urgingthe follower roller 76 to continuous contact of the cam track 75. Theposition of the cam 73, as shown in FIG. 6, is at its limit of clockwiserotation.

The pivoted follower plate or arm 77 also carries an additional follower84, appreciably arcuately spaced from the follower 76, and this secondfollower may also be in the form of a roller which is supported by aposition adjusting block 85 (FIG. 6). A pair of setscrews 86 and 87respectively bear against opposite ends of the block 85, and, by supporton the follower arm or plate 77, permit adjustment of this block along aline arranged somewhat obliquely to a tangent of a radius of thisfollower arm extending to the axis of the follower roller 84.

As will be best understood from FIGS. 5 and 6 a freely rotatable shaft90 is rotatably supported by a bearing plate 56. Accordingly, back andforth it swings therewith the end bar member unit 91 mounted through thepartition plate 56 and carries, fixed thereto, a block 93 for rotatingthis shaft. The block 93 is biased by a tension spring 94 which has oneend thereof connected to this block at 95, at a radial distance from theaxis of the shaft 90, and its other end fixed at 96 to the partitionplate 56. The block 93 has mounted thereto, by screws 97, a sine bar 98which has a guide surface 99, provided by one edge thereof, that bearsagainst the follower roller 84 for slide therealong of this follower,which thus constitutes slide means. This sliding contact of the sine barguide surface 99 and the slide means or follower roller 84 is maintainedby the constraining action of the biasing tension spring 94.Accordingly, when the pivoted follower arm or segmental plate 77 isswung back and forth by rotation of the cam 73 the slide means 84 glidesback and forth along the sine bar guide surface 99 to rotate the sinebar back and forth. The inclusion of this sine bar 98 and its wipingfollower 84 in the light valve vane manipulating mechanismadvantageously avoids a need for steep pitch of the cam track 75, whichthus facilitates wipe therealong of the follower 74.

Rotation of the shaft back and forth through an are or a portion of asingle turn is effected by the swing back and forth of the sine bar 98,such as between the points (I) and (II), indicated in FIG. 6, i.e.,between the full line position of this sine bar shown therein and thedot-dash position indicated at 199. This swing of the sine barmanipulates simultaneously the light valve vanes 17 and 18 alternatelyto advance and retract their opposed edges 19 and 20 with respect toeach other. For this purpose, the preferred form of the light valveadjusting means includes a symmetrical parallelogram mechanismcomprising a pair of opposed and substantially parallel side bar members100 and 101 (see FIG. '4, and also the dotted line showing of a portionof the former in FIG. 6). This parallelogram mechanism also includes apair of opposed and substantially parallel end bar members 102 and 103that are spaced apart in the direction of the longitudinal dimensions ofthe side bar members 100 and 101 and are pivotally connected thereto atlongitudinally spaced points 104, 105, 106, and 107. As will be bestunderstood from FIG. 4, the light valve vane 17 and the parallelogramside bar member 100 together constitute a Z-shaped member. Likewise, thelight valve vane 18 and the parallelogram side bar member 101 togetherconstitute another Z-shaped member. The end bar member 102 is mediallyfixed to the shaft 90 while the end bar member 103 is medially supportedupon a stub shaft 108 rotatably supported in like manner upon thepartition when the shaft 90 is rotated 102, so as to cause theparallelogram section of this light valve vane structure alternately tocollapse and expand.

This collapsing and expanding action of the parallelogram simultaneouslycauses the opposed vane edges 19 and 20 of the light valve vanes 17 and18 alternately to retract retrogressively from and to advanceprogressively toward or approach each other, so as alternately toincrease and decrease the intervening space which constitutes theopening in the presently improved light valve. In other words, therotation of the end bar member 102 in one direction is effected when thefollower 76 is advanced in one direction by the continued contact withthe track 75 of the cam 73 as the latter is rotated in one direction,and the rotation of this end bar member in the opposite direction iseffected when this follower is retracted in the opposite direction bycontinued contact with this cam track as the cam is rotated in theopposite direction. Thus, the point of contact of follower 76 with thecam track 75 advances linearly in radial degrees so that the squareoutput of the cam 73 causes the advancing and retracting of the opposedstraight line edges 19 and 20 of the light valve vanes 17 and 18 to besuch, relative to each other, as to adjust the width of the interveninglight-passing slot or space in increments of continuous motion which aredirectly related to f stop adjustments thereof.

It will be understood that, while the light valve vane manipulatingmechanism illustrated in FIGS. 4, 5, and 6 includes, as driving means,the servomotor 590 in housing 59, the housed gearing and clutch in box58 and the drive shaft 61 of the nulling potentiometer 600 in housing60, such mechanism may be used to advantage in adjusting the light valveopening or slot between the opposed vane edges 19 and 20 if the drive ofthis adjusting mechanism is effected by various types of electricalmotors, other than servomotors. Such other electrical motor would bedrivably connected to both of the light valve vanes through any suitablemeans, such as reduction gearing and vane manipulating mechanism, withthe operation of such motor being under the control of the personoperating the printer.

The provision of the nulling potentiometer 600 in housing 60, coupled tothe driving servomotor 590 in housing 59, isv particularly designed foradvantageous use of the light valve vane adjusting mechanism of FIGS. 4,5, and 6 in an automatic control system which desirably may beassociated with sophisticated versions of the improved printer, theoptical systems of some of which are illustrated by way of example inthe present drawings. However, a simple version of the printer embodyingthe optical system of FIGS. 1, 1A, and 18 may include position controlmeans which, on one hand, is operatively connected to a mechanical driveassociated with the camera gate drive comprising motor 34 and driveshaft 33 and, on the other hand, is operatively connected to the lightvalve vane moving means :through that portion of the mechanical drive ofthe mechanism illustrated in FIGS. 4, 5, and 6 which intervenes thedriving pinion 62 and the light valve vane adjusting parallelogrammechanism 100-108. Alternatively, such a simple single projector headprinter may have associated therewith an automatic light valve controlsystem that would embody in the position control means a signal inputpotentiometer coupled to the motor adjustment drive shaft 33, such as ata point 39 indicated in FIG. 1B, and the entire FIGS. 4, 5, and 6assembly including the servomotor 590 in housing 59 and its housedreduction gearing unit 58, the nulling or feedback signal potentiometer600 in housing 60, and a suitable summing amplifier network to which theinput signal and the nulling potentiometer signal are supplied inopposition by suitable circuit connections with this amplifier networkbeing connected to the servomotor for dictating operation of the latter.Such automatic control system, when employed with a printer opticalsystem of the type illustrated in FIG. 2 would additionally embodyanother input signal potentiometer associated with or coupled to themechanism which translates the imaging transfer lens 40 along theoptical axis. The optical system of FIGS. 1, 1A, and 1B and the FIG. 2printers may include an additional signal input potentiometer which ismanually adjusted or operated by the person operating the printer and isdeemed a selector light control input signal potentiometer. If such anautomatic control system is embodied in a printer which is characterizedby a primary projecting section and a secondary projecting section, asis proposed in FIGS. 3 and 7, each of the two projecting sections wouldhave an automatic control system of the FIG. 2 type associatedtherewith.

The FIG. 3 optical system may be embodied in such a sophisticatedprojection optical printer which includes the primary and secondaryprojecting sections in the manner illustrated in FIG. 7. A perspectiveview of optical elements of a printer which embodies the optical systemof FIG. 3, and the parts of an automatic control system associatedtherewith is shown in FIG. 7. In the latter it is indicated that thedrive shaft 33 which translates the camera 11 along the optical path maycarry any suitable takeoff point, such as that indicated at 39, a driveworm meshed with a gear 1 11 that is fixedly carried by a shaft 1 12,with the latter fixedly supporting thereon a rotatable cam 113. Asuitable cam follower 114 rides against the peripheral track 115 of thiscam 113, longitudinally to translate a toothed rack 116. A pinion 117meshed with the rack 116 as to be rotated by the latter to manipulatethe rotor of a signal generator 400, which may constitute a first inputsignal potentiometer of' the servomotor control system that serves asthe automatic control device. The mechanical elements 110 to 117inclusive, and the electrical signal generating device 400 togetherconstitute a first or camera electromechanical control transducer.

The version of the automatic servomotor control system which isillustrated, by way of example, in FIG. 7 as being associated with eachof the pair of primary and secondary projecting sections of the thereinillustrated sophisticated version of the projection optical printer, isdesigned to effect automatic adjustment of the light-passing spacebetween the opposed lightblocking vanes of the light valve in each ofthese projecting sections. It will be seen therefrom that thisservomotor control system which, for example, is associated with theprimary projecting section includes three signal generators or inputsignal potentiometers, each of which is of the conventionalthree-terminal type. These three input signal potentiometers are thepotentiometer 400 which generates a signal at output terminal 401indicative of the position of the printing lens 26 and the framework ofcamera 11 (and thus the gate 27 thereof) along the optical axis; amanually operated selector light control potentiometer 402, whichgenerates a signal at output terminal 403 indicative of the setting ofthe pointer 404 with respect to the calibrated dial 405 (the knob 406which carries this pointer being fixed on shaft 406a to rotate thepotentiometer wiper contact); and a potentiometer 407, which generates asignal at output terminal 408 indicative of the position of the imagingtransfer lens 40 along the optical axis.

1. In projection optical printing apparatus for variable enlargement andreduction of a projected image in exposing light sensitive material tothe latter, optical system comprising, in succession along the opticalaxis of a light beam path, an apertured support for a film print thatbears an image to be recorded with this support extending in a printplane transversely of and substantially normal to the optical axis withthe latter extending substantially through the center of the supportaperture, a printing lens substantially axially aligned with the opticalaxis, and a transversely extending support for light sensitive materialthrough the center of which the optical axis extends and located at aplane of printing reproductions by said printing lens; and means totranslate along the optical axis one or more oF said light sensitivematerial support, said printing lens and said film print supportrelative to the others thereof; wherein the improvement comprises as alight source subassembly preceding said film print support a. a sourceof light rays to which the light sensitive material responds forrecording thereon a replica of the projected image, b. means providingin a transverse plane an in-focus image of the light source precedingsaid film print plane, and c. a mechanically adjustable light valve insaid light source image plane comprising light-blocking and maskingtransverse means having opposed edges located at substantially equaldistances on opposite sides of said optical axis to define anintervening light-passing space with said light valve means beingsimultaneously movable both directionally toward and away from saidoptical axis and in extent at equal increments of continuous motion forinfinite variability of said intervening light-passing space.
 2. In aprojection optical printer which comprises, in succession along theoptical axis of a light beam path, a light source sub-assembly; aprojector head having a transversely arranged gate located at arelatively fixed position along the optical axis and provided with aprojecting aperture, through the center of which the optical axisextends, for translation of an image bearing strip film along a certaintransverse path past said aperture, with field collector lens meansimmediately preceding said gate for concentration in the latter of thelight rays emanating from the light source sub-assembly; a printing lensmovably translatable along said optical axis; and a transverselyarranged camera gate translatable along said optical axis with thetranslation of the latter being correlated to the translation of saidprinting lens, said camera gate being provided with a printing aperture,through the center of which the optical axis extends, for translation ofa raw stock strip film along a certain transverse path that issubstantially parallel to the image film path and past said printingaperture for exposure to the image bearing beam projected through theprinting lens from the projector gate aperture; wherein the improvementcomprises, as optical elements of said light source sub-assembly thathave fixed positions along the optical axis relative to each other; a. asource of light rays to which the raw stock film responds for recordingthereon a replica of images borne by said strip film at the projectorhead gate, b. a succeeding condenser or transfer lens assembly havingits first principal focus located at said source of light rays, c. anadjustable light valve in the remote focal plane at the second principalfocus of said transfer lens for providing an in-focus image in saidfocal plane of unmasked portions of said light rays source whenenergized with said light valve being in the form of a pair oflight-blocking and masking vanes having opposed, spaced apart edgesarranged in said focal plane and located at substantially equaldistances to opposite sides of said optical axis, d. means for movingsaid light valve vanes simultaneously both directionally toward and awayfrom said optical axis and in extent in equal increments of continuousmotion for progressive approach and retrogressive retraction of saidopposed edges toward and away from each other with substantialmaintenance of the equality of their spacings to opposite sides of saidoptical axis for adjusting with infinite variation the space interveningsaid opposed edges to effect the required change in the quantity oflight passed through the intervening space with maintenance ofsubstantial equal distribution of the light along this space, and e. atleast one achromat collector means closely flanking one side of saidlight valve.
 3. The projection optical printer of claim 2 in which adichroic mirror intervenes said condenser and the combination of saidlight valve and its flanking field lens for turNing the optical axisthrough an angle of less than 180* and for transmitting therethrough outof the optical system undesirable heat rays.
 4. The projection opticalprinter of claim 2 in which a diffuser in the form of a planotranslucent sheet having a finely ground surface is located beyond saidlight valve and precedes and achromat collector means.
 5. The projectionoptical printer of claim 2 in which means are provided to move saidlight valve vanes simultaneously, said vane moving means comprising adriven rotary cam means provided with a contoured track and followermeans urged to continuous contact of the latter, means to rotate saidcam in a manner which rotatably translates said track with the advancingpoint of contact thereof by said follower means progressing linearly inradial degrees, and means connecting said follower means to said movablelight valve vanes in a manner simultaneously to advance and retract theopposed edges of the latter relative to said optical axis.
 6. Theprojection optical printer of claim 5 in which said light valve includesa symmetrical parallelogram mechanism comprising a pair of opposed andsubstantially parallel side bar members and a pair of opposed andsubstantially parallel end bar members that are spaced apart in thedirection of the longitudinal dimensions of said side bar members andare pivotally connected at longitudinally spaced points to the latterwhereby rotation of one of said end bar members in one direction causessaid side bar members progressively to approach each other and whenrotated in the opposite direction causes said side bar membersretrogressively to retract from each other, said side bar membersrespectively carrying one of said light valve vanes for the simultaneousmotion of the opposed edges of the latter toward and away from eachother; said connecting means includes means to rotate one of said endbar members in one direction when said follower means is advanced in onedirection by contact with said cam track and to rotate it in theopposite direction when said follower means is retracted in the oppositedirection by contact with said cam track.
 7. The projection opticalprinter of claim 6 in which said follower means is in the form of apivotally mounted biased arm carrying a follower held in contact of saidcam track by the biasing of said pivoted arm whereby the latter is swungback and forth by the rotation of said cam means; and said connectingmeans is in the form of slide means carried by said follower arm forswing therewith an a sine bar connected to said rotatable parallelogramend bar member for swing of the latter thereby with said sine bar havinga generally radiating guide surface constrained toward contact of saidslide means whereby when said pivoted follower arm is swung back andforth by rotation of said cam means said slide means glides back andforth along said guide surface of said sine bar to rotate the latterback and forth.
 8. The projection optical printer of claim 2 in whichthe optical system includes an additional projector head to serve as anaerial image projector interposed between said light valve and thefirst-mentioned projector head with the latter serving as a masterprojector, said aerial image projector including a similar aperturedgate for translation therepast of an additional image bearing strip filmwhich may serve as a matte, additional field collector lens meansimmediately preceding said aerial image projector gate beyond said lightsource sub-assembly; common means supporting in succession at fixedpositions relative to each other along the optical axis said lightsource sub-assembly, said additional field collector means and saidaerial image projector gate with said common means being adjustablytranslatable along said optical axis; and an imaging transfer lensassembly interposed between the gates of said aerial image and masterprojector heads which is independently translatable along said opticalaxis.
 9. The projeCtion optical printer of claim 8 in which said lightsource sub-assembly, said condenser, said adjustable light valve withits flanking field lens, said aerial image projector, said axiallyadjustable imaging transfer lens assembly, and said master projectorwith its associated field collector means together constitute a primaryprojecting section; said optical system including an oblique lighttransmitting and reflective mirror means interposed between andoptically axially aligned with said primary projecting section and saidprinting lens; and a secondary projecting section functionally similarto said primary projecting section having its optical axis directedtoward and intercepted by the oblique reflective surface of saidinterposed mirror means for additive assembly thereat of the projectedimage outputs of said primary and secondary projecting sections; and inwhich is inserted in each of the light source sub-assemblies of theprojecting sections, between the source of light rays and condenserthereof, a swingable dichroic filter, whereby change of the angle ofincidence with respect to the optical path of at least one of thedichroic filters by swing thereof the light outputs of the two light raysources can be color corrected for identicalness.
 10. The projectionoptical printer of claim 9 in which operator-controlled drive mechanismis provided for translating at will in correlated manner said printinglens and camera gate along the optical axis thereof; and there is alsoprovided operator-controlled means for translating said imaging transferlens assembly in each of said projecting sections independently alongthe optical axis relative to said common means which supports said lightsource sub-assembly and said aerial image projector in this projectingsection, and also relative to said camera gate and printing lens;whereby in each of said projecting sections adjustment of the positionof said imaging transfer lens assembly thereof along the optical axiswill maintain in focus at the gate of said master projector thereof anyimage borne by the film translated through said aerial image projectorgate thereof.
 11. The projection optical printer of claim 2 in which isprovided position control means operatively connected to said axiallytranslatable printing lens and camera gate and to said means for movingsaid light valve vanes simultaneously toward and away from each other,said position control means being adapted to provide said light valvevane moving means with a control input proportional to printing lens andcamera gate axial translation.
 12. The projection optical printer ofclaim 11 wherein said position control means comprises printing lens andcamera gate translation apparatus for effecting said translation alongthe optical axis, a first signal generator operatively connected theretoand producing an output signal proportional to optical axis translationof said printing lens and camera gate, a second signal generatoroperatively connected to said light valve vane moving means andproducing an output signal proportional to the simultaneous movement ofsaid vanes, circuit means connected to said signal generators andcombining said output signals to produce a circuit output signal andmeans responding to the circuit output signal for generating saidcontrol input to said light valve vane moving means.
 13. The projectionoptical printer of claim 12 wherein said circuit means comprises anetwork which subtractively combines said second signal generator outputsignal with said first signal generator output signal to produce saidcircuit output signal.
 14. The projection optical printer of claim 12 inwhich is further provided a manual controller for said circuit outputsignal, said position control means including also a third signalgenerator operatively connected to said manual controller and producingan output signal proportional to the controller setting, said circuitmeans being connected also to said third signal generator for combiningall signal generator output signals to produce said circuit outputsignal.
 15. The projection optical printer or claim 12 wherein saidmeans responding to said circuit output signal comprises an electricmotor and a mechanism driven thereby to provide said control input, saidmotor driven mechanism including first and second output members coupledrespectively to said light valve vane moving means and said secondsignal generator.
 16. The projection optical printer claimed in claim 15wherein said light valve vane moving means comprises a driven rotary camhaving a contoured track coupled to said first output member for drivethereby, follower means urged to continuous contact with said track, andmeans connecting said follower means to said movable light valve vanes,said cam being rotated by said first output shaft in a manner whichrotatably translates said track with the advancing point of contactthereof of said follower means progressing linearly in radial degreeswhereby said movable light valve vanes are advanced and retractedlinearly relative to each other.
 17. The projection optical printer ofclaim 12 wherein the optical system includes an additional projectorhead to serve as an aerial image projector interposed between said lightvalve and the first-mentioned projector head with the latter serving asa master projector, and an imaging transfer lens assembly interposedbetween said aerial image and master projector heads, said positioncontrol means including further imaging transfer lens translationapparatus and another signal generator operatively connected thereto andproducing an output signal proportional to transfer lens translationalong the optical axis, said circuit means being connected also to saidlast-mentioned signal generator for combining all signal generatoroutput signals to produce said circuit output signal.
 18. The projectionoptical printer of claim 9 in which is provided, in association withsaid printing lens and camera gate, translation apparatus operativelyconnected thereto to effect axial translation thereof, a first signalgenerator operatively connected to said axial translation apparatus forproducing an output signal proportional to the axial translation of saidprinting lens and camera gate; position control means adapted to providesaid light valve moving means of said primary projecting section with acontrol input proportional to printing lens and camera gate axialtranslation, a second signal generator operatively connected to saidlight valve vane moving means for producing a second output signalproportional to the simultaneous movement of said vanes; additionaltranslation apparatus operatively connected to said imaging transferlens located in said primary projecting section to effect axialtranslation of this imaging lens, a third signal generator operativelyconnected to said imaging transfer lens translation apparatus forproducing a third output signal proportional to the axial translation ofthis imaging lens; a manual controller for said primary projectingsection, a fourth signal generator operatively connected to said manualcontroller for producing a fourth output signal proportional to thecontroller setting; circuit means connected to said signal generatorsand combining said output signals to produce a summed circuit outputsignal for generating said control input to said light valve movingmeans; and functionally similar light valve vane control means, imagingtransfer lens translation apparatus and manual controller respectivelyhaving operatively connected thereto functionally similar second, thirdand fourth signal generators associated with said secondary projectingsection, an additional secondary projecting section first signalgenerator operatively connected to said printing lens and camera gatetranslation apparatus for producing another first output signal that isproportional to the axial translation of said printing lens and cameragate, and second circuit means connected to said Secondary projectingsection first, second, third and fourth signal generators and combiningsaid output signals of these four signal generators to produce a summedcircuit output signal for generating the control input to the lightvalve moving means embodied in said secondary projecting section.